Methods and apparatus to monitor material conditioning machines

ABSTRACT

Methods and apparatus to monitor conditioning machines are disclosed herein. An example system includes a plurality of work rolls to process a continuous strip of material positioned between an entry and an exit of an apparatus. A sensor is positioned downstream from the exit of the apparatus. The sensor measures a first distance between an upper surface of the strip material and a predetermined reference. The sensor measures a second distance between the upper surface of the strip material and the predetermined reference. The first and second distances is measured at at least one of two different locations or two different instances in time as the strip material exits the apparatus. A controller compares the first distance and the second distance to detect material curvature or longbow in the strip material.

CROSS-REFERENCE TO RELATED APPLICATION

This patent arises from a continuation of U.S. application Ser. No.13/839,809, (Now U.S. Pat. No. 9,021,844) which was filed on Mar. 15,2013 and is hereby incorporated herein by reference in its entirety.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to material conditioningmachines, and more particularly, to methods and apparatus to monitormaterial conditioning machines.

BACKGROUND

Material conditioners have long been used in processing strip materialused in connection with mass production or manufacturing systems. In amanufacturing system, a strip material (e.g., a metal) is typicallyremoved from a coiled quantity of the strip material. However, uncoiledrolled metal or strip material may have certain undesirablecharacteristics such as, for example, coil set, longbow, crossbow, etc.due to shape defects and internal residual stresses resulting from themanufacturing process of the strip material and/or storing the stripmaterial in a coiled configuration.

To achieve a desired material condition, a strip material removed from acoil often requires conditioning (e.g., flattening and/or leveling)prior to subsequent processing in a roll forming machine, a stampingmachine, a laser cutter and/or other machine(s). For optimum partproduction, a strip material should have uniform flatness along itscross-section and longitudinal length and be free from any shape defectsand any internal residual stresses. Flatteners and/or levelers cansubstantially flatten a strip material to eliminate shape defects and/orrelease the internal residual stresses as the strip material is uncoiledfrom the coil roll.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example strip material in a coil condition.

FIG. 2A is a side view of an example production system having an exampleleveler configured to process a moving strip material constructed inaccordance with the teachings disclosed herein.

FIG. 2B is a plan view of the example leveler of FIG. 2A.

FIG. 3 illustrates an example configuration of work rolls of the exampleleveler of FIGS. 2A and 2B.

FIG. 4 is a front view of the example leveler of FIGS. 2A, 2B and 3.

FIG. 5 is an enlarged view of the example leveler of FIGS. 2A, 2B 3 and4 showing an example bow detection system constructed in accordance withthe teachings disclosed herein.

FIG. 6 illustrates an example system that may be used to operate theexample leveler of FIGS. 2A, 2B, 3-5.

FIG. 7 illustrates a flow diagram of an example method to implement theexample system of FIG. 6.

FIG. 8 is a block diagram of an example processor platform that may beused to implement the example methods and apparatus described herein.

DETAILED DESCRIPTION

FIG. 1 illustrates a strip material 100 in a coiled state or condition102. Coiled strip material frequently manifests undesirable materialconditions that are the result of longitudinal stretching of the stripmaterial 100 during coiling and/or as a result of remaining in thecoiled state 102 for a period of time. In particular, the coil windingprocess is usually performed under high tension, which may cause acondition commonly referred to as coil set. If significant, coil set maymanifest itself as a condition commonly referred to as longbow (e.g.,bow up/bow down) causing the strip material 100 to experience curvature(e.g., concavity) along its longitudinal axis. Longbow, for example, isdue to a surface-to-surface length differential along a longitudinallength L of the strip material 100 due to the strip material 100 beingin the coiled state 102. In other words, the strip material 100 retainscurvature (e.g., a curled or curved profile) along the longitudinallength L of the strip material 100. This undesirable condition ismanifest in an uncoiled condition or state when the strip material 100is unwound from a coil or roll 10. For example, due to being in thecoiled state 102, an upper surface 106 of the strip material 100 islonger (e.g., bent along the longitudinal length L of the strip material100) relative to an inner or bottom surface 108 of the strip material100. As an uncoiled portion 104 is pulled straight, the longer uppersurface 106 causes the shorter bottom surface 108 to curl or bend (i.e.,longbow).

Undesirable material conditions such as longbow can be substantiallyeliminated using leveling or flattening techniques. Leveling and/orflattening techniques are implemented based on the manners in whichstrip materials react to stresses imparted thereon (e.g., the amount ofload or force applied to a strip material). For example, the extent towhich the structure and characteristics of the strip material 100 changeis, in part, dependent on the amount of load, force, or stress appliedto the strip material 100.

Levelers typically bend a strip material back and forth through a seriesof work rolls to reduce internal stresses by permanently changing thememory of the strip material 100. More specifically, the work rolls arepositioned or nested to a plunge depth position required to plasticallydeform the strip material. For example, the plunge depth position can bedetermined by known material characteristics such as, for example, thethickness of the strip material, yield strength of the strip material,composition of the strip material, and/or work roll diameter, etc.

At the plunge depth position, the work rolls apply a plunge force toplastically deform the strip material 100 as the material enters theleveling machine. Bending the strip material 100 using a relatively lowplunge force maintains the strip material 100 in an elastic phase suchthat residual stresses in the strip material 100 remain unchanged. Tosubstantially reduce or eliminate residual stresses, the strip material100 is stretched beyond the elastic phase to a plastic phase to stretchthe strip material 100 across the entire thickness of the strip material100. The amount of force required to cause a metal to change from anelastic condition to a plastic condition is commonly known as yieldstrength. The plunge force applied to the strip material 100 can beincreased to transition the material from the elastic phase to theplastic phase to substantially reduce or eliminate the residual stressesof the strip material 100 that cause undesired characteristics ordeformations (e.g., such as coil set and/or longbow). Specifically,small increases in the force or load applied to the strip material 100can cause relatively large amounts of stretching (i.e., deformation) tooccur.

Although the yield strength of the strip material 100 is constant, theeffect of coil set may require a greater force to bend or stretch thetrailing edge 112 of the strip material 100 beyond the yield strength ofthe strip material compared to a force required to bend or stretch theleading edge 110 of the strip material 100 beyond the yield strength ofthe strip material 100. However, in some examples, if the strip material100 is processed with a significant plunge force (e.g., too much plungeforce is applied to the strip material 100), the plunge force may causethe upper surface 106 to curl toward the bottom surface 108 (i.e., upbow). Additionally or alternatively, coil set may vary across a width Wof the strip material 100 (e.g., between respective peripheral edges 114and 116).

As a result, nesting the work rolls based only on a plunge depthposition may not account for changes in plunge force needed alongdifferent portions (e.g., lengths) of the strip material 100 as thestrip material 100 uncoils from the roll 10. In other words, differentamounts of force (e.g., vertical force) may be needed to condition thestrip material 100 (e.g., stretch the strip material beyond its yieldstrength or prevent over stretching) as the strip material 100 isunwound from the roll 10. For example, an insufficient plunge forceprovided by a plunge depth position of the work rolls may fail tostretch or elongate a portion of the strip material 100 beyond the yieldpoint of the strip material 100, which may result in relatively minor ornegligible permanent change to internal stresses in the unstretchedportion of the strip material 100. When a plunge force applied to aportion of the strip material 100 is removed without having stretchedportions of the strip material to the plastic phase, the residualstresses remain in those portions of the strip material 100, causing thestrip material 100 to return to its shape prior to the force beingapplied. In such an instance, the strip material 100 has been flexed,but has not been bent. In some examples, the strip material 100 may beoverstretched or processed with significant plunge force or depth,causing the upper surface 106 of the strip material to bow downwardtoward to the bottom surface 108.

The example methods and apparatus disclosed herein monitor for materialcurvature, concavity or longbow in a strip material and/or provide asubstantially flat strip material 100 having minimal or significantlyreduced longbow.

To significantly reduce or eliminate longbow from the strip material100, the example methods and apparatus described herein monitor ormeasure material curvature (e.g., concavity) to monitor, detect, corrector remove longbow along the longitudinal axis of the length L of thestrip material 100. Detection of longbow enables sufficient adjustmentof a leveler and/or other flatting machine(s) to apply a sufficientforce to a strip material to effectively remove longbow effect (e.g.plastically deform the strip material 100) along an entire length of thestrip material 100 (e.g., along the longitudinal length L between theleading and trailing edges 110, 112). More specifically, to detectcurvature along the length L of the strip material 100, the exampleapparatus and methods disclosed herein monitor or detect a difference inmeasured height values between a reference (e.g., a base of a sensor)and the strip material 100 (e.g., a vertical distance differential) asthe strip material exits the levelers. For example, the measured heightvalues may be taken at least at two lateral positions (e.g., horizontalpositions) on the strip material 100 as the strip material exits aleveling machine or other flatting machine(s). The measured heightvalues may be taken at least at two lateral positions simultaneously orwithin a specific time interval(s).

For example, the example methods and apparatus detect a height ordistance (e.g., a vertical gap or space) between a reference point andthe upper surface 106 of the strip material 100 measured at a firstposition or point of the strip material 100 and a second position orpoint (e.g., downstream from the first position) as the strip material100 exits the leveler machine and travels away from the leveler machine.For example, the first and second positions are spaced apart (e.g.,horizontally) at a distance from each other and relative to an exit ofthe leveler machine. In some examples, the height positions may bemeasured simultaneously at the first and second positions (i.e.,measuring two different lateral points on the strip material 100 at thesame time). Additionally or alternatively, in some examples, the samepoint of the strip material 100 may be measured at different timeintervals as the strip material 100 moves between a first positionadjacent the exit of the leveler and a second position downstream fromthe first position (i.e., measuring the same point or location of thestrip material 100 as the point or location to be measured moves betweena first position and a second position). A difference between the firstand second measured height values is determined to monitor for, and/ordetect, material curvature. In particular, a difference between thefirst and second height positions is indicative of longbow being presentin the strip material 100. This difference may be either a positivevalue or a negative value, which indicates the direction and magnitudeto detect up bow or down bow.

As a result, the example methods and apparatus disclosed herein enable aleveler or other flatting machine to change a plunge force (e.g.,increase or reduce) applied to the strip material 100 sufficient toyield (e.g., plastically deform) the strip material to correct forlongbow (e.g., up bow/down bow). When the difference between themeasured height values is equal to a threshold or reference value (e.g.,a threshold difference around or approximately zero), longbow issubstantially removed or corrected, thereby providing significantlyimproved flatness properties and/or flat laser burning properties in thestrip material after leveling.

FIG. 2A is a side view and FIG. 2B is a plan view of an exampleproduction system 20 configured to process a moving strip material 100using an example leveler 202 disclosed herein. In some exampleimplementations, the example production system 20 may be part of acontinuously moving strip material manufacturing system, which mayinclude a plurality of subsystems that modify, condition or alter thestrip material 100 using processes that, for example, level, flatten,punch, shear, and/or fold the strip material 100. In alternative exampleimplementations, the leveler 202 may be implemented as a standalonesystem.

In the illustrated example, the example leveler 202 may be placedbetween an uncoiler 204 and a subsequent operating unit 206. In theillustrated example, the strip material 100 travels from the uncoiler204, through the leveler 202, and to the subsequent operating unit 206in a direction generally indicated by arrow 208. The subsequentoperating unit 206 may be a continuous material delivery system thattransports the strip material 100 from the leveler 202 to a subsequentoperating process such as, for example, a punch press, a shear press, aroll former, a laser cutter, etc. For example, during the levelingoperation, subsequent operations (e.g., a cutting operation performed bya laser cutter) may be performed as the strip material 100 movescontinuously through the leveler 202. In some examples, a conveyor maybe employed to transfer and/or support the strip material 100 betweenthe leveler 202 and the subsequent operating unit 206. In other exampleimplementations, sheets precut from, for example, the strip material 100can be sheet-fed through the leveler 202.

The strip material 100 may be a metallic substance such as, for example,steel or aluminum, or may be any other deformable material. In a coiledstate, the strip material 100 may be subject to variable andasymmetrical distribution of residual stresses along its width W (e.g.,a lateral axis) and length L (e.g., a longitudinal axis or centerline)that cause shape defects in the strip material 100. As the stripmaterial 100 is uncoiled or removed from the coiled roll 10, it mayassume one or more uncoiled conditions or shape defects such as, forexample, coil set and/or longbow. Failure to remove the internalstresses of the strip material 100 may cause the uncoiled strip material100 to curve or bow (e.g., upward) and damage, for example, a lasercutter as the strip material 100 is being cut by the laser cutter.

To condition the strip material 100 and remove internal stresses thatmay cause uncoilded conditions such as coil set or longbow, the stripmaterial 100 travels through the leveler 202. The leveler 202 of theillustrated example employs a plurality of work rolls 212 to reshape orwork the strip material 100 to reduce coil set and/or the internalstresses in the strip material 100 and to impart a flat shape on thestrip material 100 as it exits the leveler 202. In this manner, removalof the internal stresses significantly prevents the strip material 100from, for example, bowing and damaging, for example, a laser cutter asthe strip material 100 is being cut by the laser cutter. In other words,the internal memory of the strip material 100 is removed via the leveler202.

To detect or ensure that material curvature (e.g., longbow or bow) isremoved from the strip material 100, the example leveler 202 of theillustrated example employs a bow detection system or apparatus 214 inaccordance with the teachings disclosed herein. As described in greaterdetail below, the bow detection system 214 measures a height differenceat one or more points or positions along a length of the strip material100 (e.g., along a centerline L of FIG. 2B) as the strip material 100exits the leveler 202.

FIG. 3 illustrates an example configuration of the work rolls 212 of theexample leveler 202 of FIGS. 2A and 2B. As shown in the illustratedexample of FIG. 3, the plurality of work rolls 212 of the leveler 202are arranged as a plurality of upper work rolls 302 and lower work rolls304. To reshape or work the strip material 100, the upper work rolls 302and the lower work rolls 304 are arranged in an offset relationship(e.g., a nested or alternating relationship) relative to one another onopposing sides of the strip material 100 being processed to create amaterial path that wraps above and below opposing surfaces of thealternating upper and lower work rolls 302 and 304. Engaging opposingsurfaces of the strip material 100 using the upper and the lower workrolls 302 and 304 in such an alternating fashion facilitates releasingthe residual stresses in the strip material 100 to condition (e.g.,flatten, level, etc.) the strip material 100.

In the illustrated example, the upper and lower work rolls 302 and 304are partitioned into a plurality of entry work rolls 306 and a pluralityof exit work rolls 308. The entry work rolls 306 reshape the stripmaterial 100 by reducing the internal stresses of the strip material100. The exit work rolls 308 adjust any remaining internal stresses ofthe strip material 100 to impart a flat shape on the strip material 100as the strip material 100 exits the leveler 202. The leveler 202 of theillustrated example may also employ a plurality of idle work rolls 310positioned between and in line with the entry work rolls 306 and theexit work rolls 308. For example, the entry and exit work rolls 306 and308 may be driven via, for example, a motor and the idle work rolls 310may non-driven, but can be driven in some implementations. In someexamples, the entry work rolls 306 may be driven independent of the exitwork rolls 308 and the entry work rolls 306 can be controlledindependent of the exit work rolls 308. In some examples, the entry workrolls 306 and the exit work rolls 308 may be driven together and/orcontrolled independently of each other.

The magnitudes of the forces used to condition the strip material 100depend on the type or amount of reaction the strip material 100 has tobeing wrapped or bent about a surface of each work roll 212. As shown inFIG. 2, each work roll 212 is used to apply a load (i.e., a plunge forceF) to the strip material 100. The plunge force applied by each work roll212 to the strip material 100 is created by increasing a plunge of thework roll 212 toward the strip material 100. More specifically, to varythe plunge force, a work roll plunge can be varied by changing a centerdistance or plunge depth 312 between center axes 314 and 316 of therespective upper and lower work rolls 302 and 304. In general, for anygiven work roll plunge depth or plunge, a decreased distance orincreased plunge depth increases the tensile stress imparted to thestrip material 100 and, thus, the potential for plastic deformation,which conditions the strip material 100. In the illustrated example, theplunge of the entry work rolls 306 is set to deform the strip material100 beyond its yield strength and, thus, the plunge of the entry workrolls 306 is relatively greater than a plunge depth of the exit workrolls 308. In some example implementations, the plunge of the exit workrolls 308 can be set so that they do not deform the strip material 100by any substantial amount but, instead, adjust the shape of the stripmaterial 100 to a flat shape (e.g., the plunge of the exit work rolls308 is set so that a separation gap between opposing surfaces of theupper and lower work rolls 302 and 304 is substantially equal to thethickness of the strip material 100).

FIG. 4 illustrates a side view of the example leveler 202 of FIG. 2.Referring to FIG. 4, the leveler 202 has a frame or housing 400 thatincludes an upper frame 402 and a bottom frame 404. The upper frame 402includes an upper backup 406 mounted thereon and the bottom frame 404includes an adjustable backup 408 mounted thereon. In the illustratedexample of FIG. 4, the upper backup 406 is non-adjustable and fixed tothe upper frame 402 and the adjustable backup 408 is adjustable relativeto the upper backup 406. However, in other example implementations, theupper backup 406 may also be adjustable.

The upper backup 406 includes a row of backup bearings 410 supported bya non-adjustable flight 412 and the plurality of upper work rolls 302that are supported by the upper backup bearings 410. Thus, the upperbackup bearings 410 fix the upper work rolls 302 in place.

The adjustable backup 408 includes a row of lower backup bearings 414supported by one or more adjustable flights 416. The lower backupbearings 414 support the plurality of lower work rolls 304. In someexamples, intermediate rolls (not shown) may be positioned between theupper backup bearings 410 and the upper work rolls 302 and/or betweenthe lower backup bearings 414 and the lower work rolls 304 tosubstantially reduce or eliminate work roll slippage that mightotherwise damage the strip material 100 or mark relatively soft orpolished surfaces of the strip material 100. Generally, journals (notshown) rotatably couple the lower and upper work rolls 302 and 304 tothe frame 400 to allow rotation of the work rolls 302 and 304. The workrolls 212 are small in diameter and are backed up by the respectivebackup bearings 410 and 414 to prevent unwanted deflection along thelength of the work rolls 212.

In the illustrated example, the leveler 202 uses the adjustable backup408 (i.e., adjustable flights) to adjust the plunge or a position of thelower work rolls 304 relative to the fixed upper work rolls 302 (e.g.,to increase or decrease a plunge depth between the upper and the lowerwork rolls 302 and 304). Adjustment of the lower work rolls 304 relativeto the fixed upper work rolls 302 may enable substantially continuous orstepwise variation of the plunge of the work rolls 212, thereby enablinga substantially continuous or stepwise variation of the stress impartedto the strip material 100.

More specifically, one or more actuators or hydraulic cylinders 418 and420 move the lower backup bearings 414 via the adjustable flights 416 toincrease or decrease a plunge depth between the upper and the lower workrolls 302 and 304. In particular, the lever 202 can change the length ofthe strip material 100 by adjusting the position of the lower work rolls304 relative to the upper work rolls 302 via the actuators 418 and 420to create a longer path. Creating a longer path by increasing a plungeof the upper and lower work rolls 302 and 304 causes the strip material100 to stretch and elongate further than a shorter path created bydecreasing a plunge of the work rolls 302 and 304.

In the illustrated example of FIG. 4, the actuator 418 moves a first end422 of the adjustable flight 416 relative to a second end 424 of theadjustable flight 416 to adjust a position of the lower work rolls 302relative to the upper work rolls 304 at an entry 426 of the leveler 202(e.g., the entry work rolls 306 of FIG. 3). The actuator 420 moves thesecond end 424 of the adjustable flight 416 relative to the first end422 to adjust the position of the lower work rolls 304 relative to theupper work rolls 302 at an exit 428 of the leveler 202 (e.g., the exitwork rolls 308 of FIG. 3). In this manner, the lower backup bearings 414supported adjacent the first end 422 of the adjustable flight 416 can bepositioned at a first distance or height (e.g., a vertical distance)relative to the fixed upper work rolls 302 adjacent the entry 426 andthe lower backup bearings 414 supported adjacent the second end 424 ofthe adjustable flight 416 can be positioned at a second distance orheight (e.g., a vertical distance or a distance different from the firstheight) relative to the fixed upper work rolls 302 adjacent the exit428. In other example implementations, the position or plunge of thework rolls 212 can be adjusted by moving the upper backup 406 withrespect to the adjustable backup 408 using, for example, motor and screw(e.g., ball screw, jack screw, etc.) configurations. As noted above, todetect material curvature or longbow in the strip material 100, theexample leveler 202 of FIG. 204 includes the bow detection system 214.The bow detection system 214 of the illustrated example is positioned ator adjacent the exit 428 of the example leveler 202.

FIG. 5 illustrates an enlarged portion of the exit 428 of the exampleleveler 202 of FIGS. 2-4. More specifically, FIG. 5 illustrates anenlarged view of the example bow detection system or apparatus 214 ofFIGS. 2A, 2B and 4. Referring to FIG. 5, the bow detection system 214 ispositioned at or adjacent (e.g., near) the exit 428 of the leveler 202.More specifically, the bow detection system 214 of the illustratedexample is positioned within a dimensional envelope or outermost frameof the leveler 202. In this manner, the bow detection system 214 ispositioned or mounted inside (e.g., a dimensional envelope of) theleveler 202. Alternatively, the bow detection system 214 may bepositioned downstream (e.g., away from the exit 428 or outside adimensional envelope) of the leveler 202.

The bow detection system 214 of the illustrated example measures ordetects material curvature (e.g., concavity, convexity, up bow, downbow, etc.) of the strip material 100 to detect the presence of longbow.To measure or detect material curvature, the example bow detectionsystem 214 of the illustrated example employs a sensor module 502. Thesensor module 502 of the illustrated example is coupled or attached to aframe portion 504 of the frame 400. More specifically, the sensor module502 is supported, coupled or attached to the upper frame 402 of theleveler 202 via a mounting bracket 506. The mounting bracket 506 of theillustrated example is an L-shaped bracket having a first arm 506 acoupled to the frame portion 504 and a second arm or portion 506 bprotruding or cantilevered therefrom to support the sensor module 502.More specifically, the first arm 506 a of the mounting bracket 506 iscoupled to the upper frame 402 via a fastener 508 and the sensor module502 of the illustrated example is coupled to the second portion 506 b ofthe bracket 506 via fasteners 510. The fasteners 508, 510 of theillustrated example include washers and/or adjustable screws to enableadjustment of the sensor module 502 in a first direction 512 (e.g., avertical direction) and a second direction 514 (e.g., a horizontaldirection).

The sensor module 502 of the illustrated example includes a first sensor516 and a second sensor 518. For example, the sensors 516, 518 may beKeyence Model IL-065 sensors manufactured by Keyence America, Inc. Inother examples, the sensor module 502 may include only one sensor and/ora plurality of sensors (e.g., more than two sensors).

Each of the first and second sensors 516, 518 of the illustrated exampleis coupled or supported by a housing 520 of the sensor module 502.Additionally or alternatively, each of the first and second sensors 516,518 of the illustrated example is movably coupled to the housing 520 viaa slider 522. More specifically, each slider 522 of the illustratedexample enables independent adjustment of the first and second sensors516, 518 relative to the housing 520, the strip material 100 and/orrelative to each other, in both the first direction 512 (e.g., up anddown in a vertical direction) and the second direction 514 (e.g., sideto side in a horizontal direction). Thus, the sensor module 502 of theillustrated example enables adjustment of the first and second sensors516, 518 relative to (e.g., toward and away from) an upper surface 524of the strip material 100. Additionally, the sensor module 502 or theslider 522 of the illustrated example also enables adjustment (e.g.,left and right or side to side adjustment) of the first and secondsensors 516, 518 relative to each other and/or the exit 428 of theleveler 202 in the second direction 514 (e.g., in the horizontaldirection). Each slider 522 of the illustrated example may be configuredto enable manual adjustment of the sensors 516, 518 (e.g., viafasteners) and/or automated adjustment of the sensors 516, 518 (e.g.,via stepper motors) in the first and second directions 512, 514.

As shown in the illustrated example, the first sensor 516 is positionedat a first distance or position 526 (e.g., a horizontal distance) from acenter axis 528 of a work roll 530 of the plurality of work rolls 212.In this example, the work roll 530 is one of the plurality of exit workrolls 308 and is the closest work roll to the exit 428 of the leveler202. The second sensor 518 of the illustrated example is positioned at asecond distance or position 532 (e.g., a horizontal distance) from thefirst sensor 516 and/or the center axis 528 of the work roll 530. Forexample, the first distance 526 may be between approximately two inchesand four inches from the center axis 528 of the work roll 530 and thesecond distance 532 may be between approximately two and a half and sixinches from an axis 534 (e.g., a vertical axis) of the first sensor 516.

In the illustrated example, the first sensor 516 is also spaced at athird distance 536 (e.g., a vertical distance) from the upper surface524 of the strip material 100 and the second sensor 518 is positioned ata fourth distance 538 (e.g., a vertical distance) from the upper surface524 of the strip material 100. As shown in FIG. 5, the distances 536,538 are substantially equal or identical. For example, the first andsecond sensors 516, 518 may be positioned at a distance of betweenapproximately two inches and four inches away from the upper surface 524of the strip material 100. Alternatively, in other examples, thedistance 536 may be different from the distance 538.

Additionally or alternatively, the sensors 516, 518 of the bow detectionsystem 214 of the illustrated example are positioned or aligned relativeto the longitudinal axis L (FIG. 2B) of the strip material 100. In otherwords, the sensor module 502 and/or the sensors 516, 518 are centeredbetween peripheral edges 114, 116 of the strip material 100. However, inother examples, the sensors 516, 518 may be offset relative to thelongitudinal axis L (FIG. 2B) of the strip material 100. In someexamples, one of the sensors 516, 518 may be offset from thelongitudinal axis L and the other one of the sensors 516, 518 may bealigned with the longitudinal axis L of the strip material 100. In someexamples, the first sensor 516 may be offset relative to a first side ofthe longitudinal axis L (e.g., toward the peripheral edge 114 of thestrip material 100) and the second sensor 518 may be offset to a secondside of the longitudinal axis L (e.g., toward the peripheral edge 116 ofthe strip material 100).

As described in detail below, each of the sensors 516, 518 iscalibrated. Each sensor 516, 518 is calibrated with a reference valuebecause each of the sensors 516, 518 can be positioned at differentheights or offsets relative to the upper surface 524 of the stripmaterial 100. For example, the sensors 516, 518 are calibrated such thateach base 540 of the respective sensors 516, 518 provides a referencefor measuring a height or vertical distance between the upper surface524 of the strip material 100 and the base 540 of each of the sensors516, 518. Thus, the base 540 of the first sensor 516 may be at a firstheight or distance relative to the upper surface 524 of the stripmaterial 100 and the base 540 of the second sensor 518 may be at asecond height or distance relative to the upper surface 524. To providethe reference point or position 540 for each of the respective sensors516, 518, the first and second sensors 516, 518 of the illustratedexample are each calibrated (e.g. independently of each other) toprovide an initial value or reference (e.g., a reference value or adistance corresponding to the distances 516, 516) indicative of thestrip material 100 having a desired flatness characteristic.

In some examples, the reference points or positions of the sensors 516,518 are calibrated manually based on operator verification. For example,the leveler 202 is adjusted to a particular plunge depth based on thecharacteristics of the strip material 100. A leveled portion of thestrip material 100 is sheared and inspected (e.g., visually inspected)for the presence of longbow (e.g., up bow/down bow). When longbow is notpresent in the test material (i.e., when the portion of the shearedstrip material 100 is substantially flat and substantially free of upbow or down bow), the positions (e.g., the vertical positions) of thesensors 516, 518 are measured, indicated or recorded as thepredetermined or calibrated reference values (e.g., threshold values,distances corresponding to the distances 536, 538) for the respectivesensors 516, 518. For example, the calibrated or reference values of therespective distances 536, 538 associated with the sensors 516, 518 areindicated or recorded as reference positions or heights (e.g., referencevalues) between the base 540 of the respective sensors 516, 518 and theupper surface 524 of the strip material 100 during calibration. In turn,during operation, the distance 536 between the base 540 of the firstsensor 516 and the upper surface 524 is measured based on the previouslydetermined or calibrated reference value (e.g., the calibrated distancevalue) of the first sensor 516 and the distance 538 between the base 540of the second sensor 518 and the upper surface 524 is measured based onthe previously determined or calibrated reference value (e.g., thecalibrated distance value) of the second sensor 518. Thus, duringoperation, each of the sensors 516, 518 provides a signal representativeof a measured distance between the base 540 of the respective sensors516, 518 and the upper surface 524 of the strip material 100 based ontheir respective calibrated or predetermined reference values. Changesin the distances measured by the sensors 516, 518 compared to thethreshold value (e.g., a near zero value) is indicative of longbow.

Alternatively, calibration plates having a known thickness may bepositioned between the upper and lower work rolls 302 and 304. Forexample, an operator may position the calibration plates between theupper and lower work rolls 302 and 304 prior to each production run.With the calibration plates positioned between the upper and lower workrolls 302, 304, the lower work rolls 304 are moved toward the upper workrolls 302 until the upper and lower work rolls 302 and 304 engage orclose against opposing surfaces of the calibration plates. With thecalibration plates in position, the measured height values of therespective distances 536, 538 are measured between the base 540 of therespective sensors 516, 518 and the calibration plates to define thepredetermined or calibrated reference value for each of the sensors 516,518 (e.g., a calibrated reference value).

With the reference point being measured or determined (e.g., when thefirst and second sensors 516, 518 are calibrated), the bow detectionsystem 214 of the illustrated example measures the height or distance536 between the base 540 of the first sensor 516 and the upper surface524 of the strip material 100 and the height or distance 538 between thebase 540 of the sensor 518 and the upper surface 524 of the stripmaterial 100. The measured height values are based on the predeterminedcalibrated reference values of the respective sensors 516, 518. The bowdetection system 214 of the illustrated example then calculates adifference between the measured values representative of the distances536, 538 to detect material curvature or longbow. The calculateddifference is compared to the threshold value (e.g., a near zero value).If a magnitude of the calculated difference of height values of therespective distances 536, 538 exceeds the threshold, then the calculateddifference is indicative of longbow. Further, a negative or positivevalue of the calculated difference is indicative of down bow or up bow(e.g., the direction of the longbow).

In other words, to detect material curvature or longbow, the example bowdetection system 214 of the illustrated example monitors or detects adifference (e.g., a vertical distance differential) between the distanceor height 536 (e.g., based on the calibrated reference value) at a firstposition on the strip material 100 associated with the first sensor 516,and a distance or height 538 (e.g., based on the calibrated or referencevalue) at a second position on the strip material 100 associated withthe second sensor 518. In some examples, the example bow detectionsystem 214 of the illustrated example measures a difference between theupper surface 524 of the strip material 100 and each base 540simultaneously along more than two different locations (e.g., twohorizontal positions) associated with the sensors 516, 518 on the stripmaterial 100 as the strip material 100 exits the leveler 202.

Alternatively, a first height value measured by the first sensor 516 maybe compared with a second height value measured by the first sensor 516as the strip material 100 moves along the production system 20.Likewise, a first height value measured by the second sensor 518 may becompared to a second height value measured by the second sensor 518 asthe strip material 100 moves along the production system 20. In otherwords, in some such examples, the sensor module 502 may employ only onesensor to detect material curvature or longbow.

The bow detection system 214 of the illustrated example includes aplate, conveyor, and/or platform 544 that receives or supports the stripmaterial 100 as the strip material 100 exits the work rolls 212. Morespecifically, the strip material 100 is supported on the conveyor 544 toprevent or reduce deflection of the strip material 100 in a downwarddirection as the strip material 100 exits the leveler 202 and movesacross the sensors 516, 518 in the second direction 514. In this manner,the sensors 516, 518 can read or detect more accurately the measuredheight values representative of the distances 536, 538 between the base540 and the upper surface 524 of the strip material 100, therebyresulting in a more accurate detection of material curvature or longbow.

In operation, a differential between the measured height values of therespective distances 536, 538 associated with the respective sensors516, 518 is indicative of the presence of material curvature or longbowin the strip material 100. For example, a difference between themeasured values representative of the distances 536, 538 that is lessthan (e.g., has a negative value) zero is indicative of up bow and ameasured difference between the measured values representative of thedistances 536, 538 that is greater than (e.g., has a positive value)zero is indicative of down bow. Therefore, the sensor module 502 alsoprovides an indication of the direction and/or magnitude of stressespresent in the strip material 100 that may result in longbow.

As a result, the example methods and apparatus disclosed herein enablethe leveler 202 (or other flatting machine) to change or adjust (e.g.,increase or reduce) a plunge force applied to the strip material 100sufficient to yield (e.g., plastically deform) the strip material 100 tocorrect for longbow (e.g., up bow/down bow). When the measureddifference between the distances 536, 538 associated with the sensor516, 518 is substantially zero, longbow or material curvature issubstantially removed and the strip material 100 is conditioned to havea substantially flat characteristic. Removal of material curvaturesignificantly reduces stress in the strip material 100 to providesignificantly improved flatness properties and/or flat laser burningproperties in the strip material 100 after leveling.

However, when the sensor module 502 detects that longbow is present(e.g., a difference between the measured height values associated withthe distances 536, 538), the example leveler 202 of the illustratedexample may provide an indication to an operator to adjust (e.g., eitherreduce or increase) the plunge depth of the of the work rolls 212.Additionally or alternatively, the example leveler 202 may automaticallyadjust the plunge position or depth of the work rolls 212 based on thestrip material 100 characteristics and the detected or measured heightdifferential value. For example, a difference between the measuredvalues representative of the respective distances 536, 538 associatedwith the first and second sensors 516, 518 of approximately 0.005 inchesmay require a plunge adjustment of approximately 0.001 inches to removeor correct material curvature or longbow in the strip material 100.Further, depending on the differential being a negative or positivevalue, the leveler 202 may be adjusted to increase or decrease theplunge depth by approximately 0.001 inches. In some examples, if thedifference is greater than a threshold value (e.g., a maximum differencevalue), the example leveler 202 or production system 20 may generate analarm and/or automatically stop a production run.

FIG. 6 is a block diagram of an example system or apparatus 600 forautomatically monitoring and conditioning the strip material 100. Inparticular, the example apparatus 600 may be used in connection withand/or may be used to implement the example leveler 202 of FIGS. 2A, 2Band 3-5 or portions thereof to adjust a plunge depth of the work rolls212 based on a measured difference detected or provided by the sensormodule 502. The example apparatus 600 may also be used to implement afeedback process to adjust a plunge depth of the entry and/or exit workrolls 306 and 308 (FIG. 3) to condition the strip material 100 based onthe measured height difference provided by the sensor module 502.

The example system 600 may be implemented using any desired combinationof hardware, firmware, and/or software (e.g., a PLC). For example, oneor more integrated circuits, discrete semiconductor components, and/orpassive electronic components may be used. Additionally oralternatively, some or all of the blocks of the example system 600, orparts thereof, may be implemented using instructions, code, and/or othersoftware and/or firmware, etc. stored on a machine accessible mediumthat, when executed by, for example, a processor system (e.g., theprocessor platform 810 of FIG. 8) perform the operations represented inthe flowchart of FIG. 7. Although the example system 600 is described ashaving one of each block described below, the example system 600 may beprovided with two or more of any block described below. In addition,some blocks may be disabled, omitted, or combined with other blocks.

As shown in FIG. 6, the example system 600 includes a user interface602, a controller 604, a plunge position detector 606, a plunge depth orposition adjustor 608, a sensor module interface 610, a comparator 612,a storage interface 614, and a calibrator interface 616, all of whichmay be communicatively coupled as shown or in any other suitable manner.

The user interface 602 may be configured to determine strip materialcharacteristics. For example, the user interface 602 may be implementedusing a mechanical and/or graphical user interface via which an operatorcan input the strip material characteristics. The materialcharacteristics can include, for example, a thickness of the stripmaterial 100, the type of material (e.g., aluminum, steel, etc.), yieldstrength data, etc. In some examples, the storage interface 614 canretrieve a plunge depth value from a look-up table or data structurehaving start-up plunge depth settings for different material types basedon, for example, material thickness values and/or yield strength valuesreceived by the user interface 602. Additionally or alternatively, anoperator can manually select the plunge depth of the work rolls 212 byentering a plunge depth valve via the user interface 602. In otherexamples, an operator or other user can manually set the initial plungedepth of the work rolls 212. The user interface 602 may be configured tocommunicate the strip material characteristics to the controller 604and/or the plunge position adjustor 608.

The plunge position adjustor 608 may be configured to obtain stripmaterial characteristics from the user interface 602 to set the plungeor vertical positions of the work rolls 212 (e.g., the distance betweenthe upper and lower work rolls 302 and 304 of FIG. 3). In some examples,the plunge position adjustor 608 may retrieve predetermined plungeposition values from the storage interface 614 and determine the plungeposition of the work rolls 212 based on the strip material inputcharacteristics from the user interface 602.

More specifically, the controller 604 may cause the plunge positionadjustor 606 to automatically adjust the entry and exit work rolls 306and 308 to predetermined entry and exit work roll plunge depthscorresponding to the particular strip material data provided by the uservia the user input interface 602. For example, the controller 604 and/orplunge position adjustor 608 can determine the plunge depth of the entrywork rolls 306 and/or the exit work rolls 308 required to condition orprocess the strip material 100 based on the strip materialcharacteristics. For example, the entry work rolls 306 may be adjustedto provide a plunge depth that is deeper (e.g., greater) than the plungedepth of the exit work rolls 308.

To adjust the plunge depth of the work rolls 212, the plunge positionadjustor 608 causes the actuators 418 and 420 (FIG. 4) to adjust theplunge depth positions of the entry work rolls 306 and/or the exit workrolls 308. For example, the controller 604 may command the plungeposition adjustor 606 to supply or deliver a pressurized control fluidto the actuators 418 and 420 sufficient to position the adjustableflights 416 and, thus, the backup bearings 414 relative to the upperwork rolls 302 to provide desired plunge depths.

The plunge position detector 608 may be configured to sense or detectthe plunge depth position values of the work rolls 212. For example, theplunge position detector 606 can detect the vertical position ordistance between the work rolls 212 (i.e., the upper and lower workrolls 302 and 304) to achieve a particular plunge depth position. Todetect the position of the plunge depth, the plunge position detector606 receives a position signal value via, for example, position sensorsassociated with the actuators 418, 420. The plunge position detector 606can then communicate the plunge depth position value to the controller604 and/or the comparator 612.

Additionally, the sensor interface 610 may be configured to communicatewith the sensors 516, 518. More specifically, the sensor interface 610may be configured to receive values representative of the measureddistances 536, 538 between the base 540 and the upper surface 524 of thestrip material 100 provided by the respective sensors 516, 518. Thesensor interface 610 may be configured to communicate the measuredvalues to the comparator 612, the controller 604 and/or the plungeposition adjustor 608. In some examples, the sensor interface 610 may beconfigured to determine or calculate the difference value between themeasured value representative of the height or distance 536 provided bythe first sensor 516 and the measured value representative of the heightor distance 538 provided by the second sensor 518. In some examples, thecomparator 612 and/or the controller 604 may be configured to obtain themeasured distance values corresponding to the distances 536, 538 fromthe sensor interface 610 and may be configured to determine thedifference value by comparing the measured distance values obtained fromthe sensor interface 610. For example, the sensor interface 610, thecomparator 612 and/or the controller 604 may be configured to performcomparisons, calculate or otherwise obtain a difference or differentialvalue between the first and second measured values. Based on thecomparisons, the sensor interface 610, the comparator 612 and/or thecontroller 604 can determine if the differential value deviates from athreshold or reference (e.g., a near zero value, etc.). The sensorinterface 610, the comparator 612 and/or the controller 604 may thencommunicate the results of the comparisons to the plunge positionadjustor 606 to adjust a plunge depth of the work rolls 212.

The calibrator 616 may be configured to calibrate or determine and/orrecord the calibrated reference value (e.g., an initial value orreference value indicative of the strip material 100 having a desiredflatness characteristic) of the first and second sensors 516, 518. Forexample, the calibrator 616 may be configured to initiate when a userinput command is selected via the user input interface 602. For example,during a pre-production or test run, the calibrator 616 may beconfigured to calibrate a reference value based on the strip material100 having substantially flat characteristics. For example, after avisual inspection determines that the strip material 100 issubstantially flat, the calibrator 616 may be initiated or configured torecord or set the reference value (e.g., a predetermined referencevalue) at a distance that corresponds to the distances 536, 538 of therespective sensors 516, 518. The calibrator 616 may be configured tocommunicate this initial position or calibrated reference value to thecomparator 612, the sensor interface 610 and/or the controller 604. Insome examples, the calibrator 616 may be configured to communicate thecalibrated reference value with the storage interface 614, thecomparator 612, the controller 604 and/or the sensor interface 610.

In some examples, the calibrator 616 may initiate a calibration of thesensors 516, 518 prior to processing the strip material 100 through theleveler 202. Additionally or alternatively, the calibrator 616 may beconfigured to automatically initiate calibration of the sensors 516, 518prior to beginning a production run.

In some examples, calibration plates having a known thickness may bepositioned between the upper and lower work rolls 302 and 304 and thecalibrator 616 may be configured to instruct the plunge positionadjustor 606 to move the lower work rolls 304 toward the upper workrolls 302 until the upper and lower work rolls 302 and 304 engage orclose against opposing surfaces of the calibration plates. For example,an operator may position the calibration plates between the upper andlower work rolls 302 and 304. Once the work rolls are in the closedposition, the calibrator 616 can set the distance value 536, 538 as thereference value(s) (e.g., a base value).

The storage interface 614 may be configured to store data values in amemory such as, for example, the system memory 813 and/or the massstorage memory 828 of FIG. 8. Additionally, the storage interface 614may be configured to retrieve data values from the memory (e.g., aplunge depth position structure and/or a plunge depth pressurestructure). For example, the storage interface 614 may access a datastructure to obtain plunge position values from the memory andcommunicate the values to the plunge position adjustor 606. The storageinterface 614 may be configured to store the reference value provided bythe sensor interface 610 and/or the calibrator 616.

FIG. 7 illustrates a flow diagram of an example method 700 that may beused to implement the example system 600 of FIG. 6. In some exampleimplementations, the example method 700 of FIG. 7 may be implementedusing machine readable instructions comprising a program for executionby a processor (e.g., the processor 812 of the example processor system800 of FIG. 8). For example, the machine readable instructions may beexecuted by the controller 604 (FIG. 6). The program may be embodied insoftware stored on a tangible medium such as a CD-ROM, a floppy disk, ahard drive, a digital versatile disk (DVD), or a memory associated withthe processor 812 and/or embodied in firmware and/or dedicated hardware.Although the example programs are described with reference to the flowdiagram illustrated in FIG. 7, persons of ordinary skill in the art willreadily appreciate that many other methods of implementing the examplelever 202 may alternatively be used. For example, the order of executionof the blocks may be changed, and/or some of the blocks described may bechanged, eliminated, or combined.

For purposes of discussion, the example method 700 of FIG. 7 isdescribed in connection with the example leveler 202 of FIGS. 2A, 2B,and 3-5 and the example apparatus 600 of FIG. 6. In this manner, each ofthe example operations of the example method 700 of FIG. 7 is an examplemanner of implementing a corresponding one or more operations performedby one or more of the blocks of the example apparatus 600 of FIG. 6.

Turning in detail to FIG. 7, the system 700 receives strip materialcharacteristics information (block 702). For example, a user can inputthe material characteristics via a user interface such as, for example,the user interface 602 of FIG. 6.

The plunge depth of the work rolls 212 is adjusted based on the stripmaterial characteristics (block 704). For example, the plunge positionadjustor 606 delivers pressurized control fluid to the respectiveactuators 418 and 420. More specifically, as noted above, the plungeposition adjustor 606 adjusts the plunge position of the work rolls 212at the entry 426 of the leveler 202 (e.g., the entry work rolls 306) andthe plunge position of the work rolls 212 at the exit 428 of the leveler202 (e.g., the exit work rolls 308). After the plunge depth is set, thestrip material 100 is processed via the leveler 202.

In operation, variations in the forces may be required to plunge thestrip material 100 beyond its yield strength due to, for example, theeffects of coil set or longbow. As the strip material is fed through theleveler 202, the sensor module 610 monitors a distance (e.g., a verticaldistance) between the strip material 100 and a base or referencelocation (block 706). For example, the sensor interface 610 monitorsand/or reads one or more distance values corresponding to the distances536, 538 as the strip material 100 is processed by the leveler 202. Forexample, the base or reference value may be the calibrated referencevalue determined during calibration of the sensors 516, 518 by measuringthe distances 536, 538 when the strip material 100 has a known flatnesscharacteristic determined via, for example, visual inspection of asheared portion of the strip material 100.

As the strip material 100 exits the leveler 202, a first sensor providesa first signal (block 708). For example, the first signal isrepresentative of a measured value corresponding to the distance 536between the base 540 of the first sensor 516 and the upper surface 524of the strip material 100. The first signal or value measured by thefirst sensor 516 may be communicated to the sensor interface 610, thecomparator 612 and/or the controller 604.

A second sensor also provides a second signal (block 710). For example,the second signal is representative of a measured value corresponding tothe distance 538 between the base 540 of the second sensor 518 and theupper surface 524 of the strip material 100. For example, the secondsignal or value measured by the second sensor 518 may be communicated tothe sensor interface 610, the comparator 612 and/or the controller 604.In some examples, the first and second signals are providedsimultaneously to the sensor interface 610, the comparator 612 and/orthe controller 604.

To detect material curvature, the comparator 612, the sensor interface610 and/or the controller 604 compares the first value representative ofthe first signal and a second value representative of the second signal(block 712). For example, the first value of the first signal iscompared with the second value of the second signal to determine orcalculate a difference between the first and second values. For example,the comparator 612, the sensor interface 610 and/or the controller 604may be configured to determine or calculate the difference between thefirst and second measured values provided by the first and secondsignals (e.g., the sensors 516, 518).

The comparator 612, the sensor interface 610 and/or the controller 604then determines if the comparison between the first and second measuredvalues is indicative of a plunge depth adjustment (block 714). Forexample, the comparator 612, the sensor interface 610 and/or thecontroller 604 determines if the difference between the first and secondmeasured values is substantially equal to a threshold value such as, forexample, a zero value or a near zero value. If the calculated differenceis equal to the threshold value, then the method 700 returns to block706. In some examples, the threshold value may have an error or buffer(e.g., a value or range). For example, the error or buffer may be thethreshold value plus or minus a value such as, for example, 0.001. Thus,a calculated difference that falls within the error or buffer rangewould result in the calculated difference being equal to the thresholdvalue.

If the calculated difference deviates from the threshold value, thecomparator 612, the sensor interface 610 and/or the controller 604determines if the comparison value (e.g., the calculated differencevalue) is within an acceptable range (block 716). For example, thecomparison value may deviate from the threshold value if the calculateddifference value is greater than or less than the threshold value (e.g.,near zero).

If the difference is within the acceptable range, then the plunge depthposition of the work rolls is adjusted (block 718). For example, thecomparator 612, the sensor interface 610 and/or the controller 604determines a necessary plunge depth adjustment value and causes theplunge position adjustor 606 to adjust (e.g., increase or decrease) aplunge depth of the work rolls 212. For example, the plunge positionadjustor 606 adjusts the plunge depth based on the value provided by thecalculated difference between the first and second distance values. Forexample, a difference value of approximately 0.005 inches may cause theplunge position adjustor 606 to adjust the plunge of one or more of thework rolls 212 by 0.001 inches. Further, depending on the differencevalue having a positive or negative value, the adjustment may be towardthe closed position (e.g., the work rolls 212 move toward each other) orthe open position (e.g., the work rolls 212 move away from each other).

The comparator 612, the sensor interface 610 and/or the controller 604determines if the production run is complete (block 720). If theproduction is not complete at block 720, the method 700 returns to block706. If the comparator 612, the sensor interface 610 and/or thecontroller 604 determines that the production run is complete at block720, the method 700 ends.

If the difference value is outside of the acceptable range at block 714,then an alarm is initiated (block 722). The alarm, for example, alertsan operator to reset the production run. Additionally or alternatively,in some examples, when the alarm is initiated, the comparator 612, thesensor interface 610 and/or the controller 604 may also command thecalibrator 616 to initiate (e.g., automatically) a calibration routineto calibrate the sensors 516, 518.

FIG. 8 is a block diagram of an example processor platform 800 capableof executing or processing the methods or instructions of FIG. 7 toimplement the apparatus 600 of FIG. 6 and/or the leveler 202 of FIGS.2A, 2B and 3-5. The processor platform 800 can be, for example, aserver, a computer, a programmable logic circuit (PLC), and/or any othertype of computing device.

The processor platform 800 of the illustrated example includes aprocessor 812. The processor 812 of the illustrated example is hardware.For example, the processor 812 can be implemented by one or moreintegrated circuits, logic circuits, microprocessors or controllers fromany desired family or manufacturer.

The processor 812 of the illustrated example includes a local memory 813(e.g., a cache). The processor 812 of the illustrated example is incommunication with a main memory including a volatile memory 814 and anon-volatile memory 816 via a bus 818. The volatile memory 814 may beimplemented by Synchronous Dynamic Random Access Memory (SDRAM), DynamicRandom Access Memory (DRAM), RAMBUS Dynamic Random Access Memory (RDRAM)and/or any other type of random access memory device. The non-volatilememory 816 may be implemented by flash memory and/or any other desiredtype of memory device. Access to the main memory 814, 816 is controlledby a memory controller.

The processor platform 800 of the illustrated example also includes aninterface circuit 820. The interface circuit 820 may be implemented byany type of interface standard, such as an Ethernet interface, auniversal serial bus (USB), and/or a PCI express interface.

In the illustrated example, one or more input devices 822 are connectedto the interface circuit 820. The input device(s) 822 permit(s) a userto enter data and commands into the processor 812. The input device(s)can be implemented by, for example, a keyboard, a button, a touchscreen,a mobile device (e.g., a cell phone, a tablet such as an IPad™), atrack-pad, and/or a voice recognition system.

One or more output devices 824 are also connected to the interfacecircuit 820 of the illustrated example. The output devices 824 can beimplemented, for example, by display devices (e.g., a light emittingdiode (LED), an organic light emitting diode (OLED), a liquid crystaldisplay, a cathode ray tube display (CRT), a touchscreen, a tactileoutput device, a light emitting diode (LED), a printer and/or speakers).The interface circuit 820 of the illustrated example, thus, typicallyincludes a graphics driver card, a graphics driver chip or a graphicsdriver processor.

The interface circuit 820 of the illustrated example also includes acommunication device such as a transmitter, a receiver, a transceiver, amodem and/or network interface card to facilitate exchange of data withexternal machines (e.g., computing devices of any kind) via a network826 (e.g., an Ethernet connection, a digital subscriber line (DSL), atelephone line, coaxial cable, a cellular telephone system, etc.).

The processor platform 800 of the illustrated example also includes oneor more mass storage devices 828 for storing software and/or data.Examples of such mass storage devices 828 include floppy disk drives,hard drive disks, compact disk drives, Blu-ray disk drives, RAIDsystems, and digital versatile disk (DVD) drives.

Coded instructions 832 to implement the method of FIG. 7 may be storedin the mass storage device 828, in the volatile memory 814, in thenon-volatile memory 816, and/or on a removable tangible computerreadable storage medium such as a CD or DVD.

From the foregoing, it will be appreciated that the above disclosedmethods, apparatus and articles of manufacture use distance differencevalues to determine if a sufficient force is applied to plasticallydeform or yield the strip material (e.g., the strip material 100)passing through nested work rolls (e.g., the work rolls 212) to removelongbow or material curvature (e.g., material concavity). Morespecifically, measured distances (e.g., vertical distances) can be usedto determine if the force provided by the work rolls 212 is sufficientto plunge (e.g., stretch or bend) the strip material 100 beyond itsyield strength to release internal stresses (e.g., remove coil set orlongbow) in the strip material 100 to provide substantially flat stripmaterial 100.

Although certain example methods, apparatus and articles of manufacturehave been disclosed herein, the scope of coverage of this patent is notlimited thereto. On the contrary, this patent covers all methods,apparatus and articles of manufacture fairly falling within the scope ofthe claims of this patent.

The invention claimed is:
 1. A system comprising: a plurality of workrolls to process a continuous strip of material positioned between anentry and an exit of an apparatus; a sensor positioned downstream fromthe exit of the apparatus, the sensor to measure a first distancebetween an upper surface of the strip material and a predeterminedreference, the sensor to measure a second distance between the uppersurface of the strip material and the predetermined reference, the firstand second distances being measured at at least one of two differentlocations or two different instances in time as the strip material exitsthe apparatus; and a controller to compare the first distance and thesecond distance to detect material curvature or longbow in the stripmaterial.
 2. The system of claim 1, wherein the controller is todetermine a difference value between the first measured distance and thesecond measured distance and to compare the determined difference valueto a threshold value, and wherein the controller detects the materialcurvature indicative or longbow along a longitudinal length of the stripmaterial when the determined difference value deviates from thethreshold value.
 3. The system of claim 2, further comprising a plungeadjustor to adjust a plunge depth of the work rolls when the differencevalue deviates from a threshold value.
 4. The system of claim 1, whereinthe predetermined reference comprises a height between a base of thesensor and the upper surface of the strip material indicative of thestrip material having a desired flatness characteristic substantiallyfree of longbow.
 5. The system of claim 1, wherein the predeterminedreference comprises a calibrated height between the upper surface of thestrip material and a base of the sensor determined when the stripmaterial is free of longbow.
 6. The system of claim 1, wherein thesensor comprises only one sensor.
 7. The system of claim 1, wherein thesensor is mounted at a lateral distance from a central axis of a workroll adjacent the exit of the apparatus.
 8. The system of claim 7,wherein the lateral distance is approximately between 6 inches and 24inches from at least one of the central axis of the work roll or theexit of the apparatus.
 9. The system of claim 1, wherein the sensor isaligned with a center longitudinal axis of the strip material, thecenter longitudinal axis being parallel to a direction of travel of thestrip material between the entry and the exit.
 10. The system of claim1, wherein the sensor is coupled to a frame of the apparatus via aslider, the slider to enable independent adjustment of the sensor in afirst direction relative to at least one of the frame or the stripmaterial and a second direction non-parallel to the first direction. 11.A method to detect material curvature in a strip material, the methodcomprising: processing a strip material via a plurality of work rollspositioned between an entry and an exit of an apparatus; obtaining afirst measured distance value between a predetermined reference and afirst location on an upper surface of the strip material downstream fromthe exit of the apparatus as the strip material exits the work rolls;obtaining a second measured distance value between the predeterminedreference and a second location on the upper surface of the stripmaterial downstream from the exit of the apparatus as the strip materialexits the work rolls, the first location being different than the secondlocation; and comparing the first measured distance value and the secondmeasured distance value to detect material curvature or longbow in thestrip material.
 12. The method of claim 11, wherein comparing the firstand second measured distance values comprises calculating a differencebetween the first measured distance value and the second measureddistance value.
 13. The method of claim 12, wherein comparing the firstand second measured distance values further comprises comparing thecalculated difference between the first and second measured distancevalues to a threshold value.
 14. The method of claim 13, whereindetecting material curvature or longbow comprises detecting materialcurvature indicative of longbow along a longitudinal axis of the stripmaterial when the calculated difference deviates from the thresholdvalue.
 15. The method of claim 11, further comprising obtaining thefirst and second measured distance values via only one sensor.
 16. Themethod of claim 15, further comprising determining the predeterminedreference comprises measuring a distance between a base of the sensorand an upper surface of the strip material when the strip material has adesired flatness characteristic substantially free of longbow.
 17. Themethod of claim 11, further comprising determining whether thedifference value is a positive value or a negative value and increasingor decreasing a plunge value based on the difference value beingpositive or negative.
 18. The method of claim 11, further comprisingadjusting a plunge depth of the work rolls if the difference valuedeviates from a threshold value.
 19. The method of claim 11, whereinobtaining the first measured distance value comprises measuring a firstvertical distance, via a sensor, between the first location on the uppersurface of the strip material and a base of the sensor and obtaining thesecond measured distance value comprises measuring a second verticaldistance, via the sensor, between the second location on the uppersurface of the strip material and the base of the sensor.
 20. The methodof claim 11, further comprising obtaining the first and second measureddistance values at two different instants in time as the strip materialexits the apparatus.
 21. A machine accessible medium having instructionsstored thereon that, when executed, cause a machine to at least: processa strip material via a plurality of work rolls positioned between anentry and an exit of an apparatus; obtain a first measured distancevalue between a predetermined reference and a first location on an uppersurface of the strip material downstream from the exit of the apparatusas the strip material exits the work rolls; obtain a second measureddistance value between the predetermined reference and a second locationon the upper surface of the strip material downstream from the exit ofthe apparatus as the strip material exits the work rolls, the firstlocation being different than the second location; and compare the firstmeasured distance value and the second measured distance value to detectmaterial curvature or longbow in the strip material.
 22. The machineaccessible medium as defined in claim 21 having instructions storedthereon that, when executed, cause the machine to calculate a differencebetween the first measured distance value and the second measureddistance value.
 23. The machine accessible medium as defined in claim 22having instructions stored thereon that, when executed, cause themachine to compare the calculated difference between the first andsecond measured distance values to a threshold value.
 24. The machineaccessible medium as defined in claim 23 having instructions storedthereon that, when executed, cause the machine to detect materialcurvature indicative of longbow along a longitudinal axis of the stripmaterial when the calculated difference deviates from the thresholdvalue.
 25. The machine accessible medium as defined in claim 21 havinginstructions stored thereon that, when executed, cause the machine toobtain the first and second measured distance values via only onesensor.
 26. The machine accessible medium as defined in claim 25 havinginstructions stored thereon that, when executed, cause the machine todetermine the predetermined reference by measuring a distance between abase of the sensor and an upper surface of the strip material when thestrip material has a desired flatness characteristic substantially freeof longbow.
 27. The machine accessible medium as defined in claim 21having instructions stored thereon that, when executed, cause themachine to determine whether the difference value is a positive value ora negative value and increasing or decreasing a plunge value based onthe difference value being positive or negative.
 28. The machineaccessible medium as defined in claim 21 having instructions storedthereon that, when executed, cause the machine to adjust a plunge depthof the work rolls if the difference value deviates from a thresholdvalue.
 29. The machine accessible medium as defined in claim 21 havinginstructions stored thereon that, when executed, cause the machine toobtain the first measured distance value by measuring a first verticaldistance, via a sensor, between the first location on the upper surfaceof the strip material and a base of the sensor and obtain the secondmeasured distance value by measuring a second vertical distance, via thesensor, between the second location on the upper surface of the stripmaterial and the base of the sensor.
 30. The machine accessible mediumas defined in claim 21 having instructions stored thereon that, whenexecuted, cause the machine to obtain the first and second measureddistance value at two different instants in time as the strip materialexits the apparatus.